As part of the Centre for High Carbon Capture Cropping (CHCx3) Crops to Products Workshop, Alex Sparrow from UK Hempcrete Ltd presents: ISO Hemp Blocks: hempcrete at scale for the mainstream
construction industry
The workshop was part of Agri-TechE’s Agri-Tech Week 2023 – https://www.agri-tech-e.co.uk/microsite-page/agri-tech-week-2023/
For more on the CHCx3: https://www.niab.com/research/agronomy-and-farming-systems/centre-high-carbon-capture-cropping
Our next speaker is Alex Sparrow who is the to and MD of UK hre limited um and again another partner in the CHC 3 project and Alex’s talk is going to be on ISO hemp blocks hemp at scale for the mainstream construction industry what I
Called it I should have put that on the slide shouldn’t I um yes so thanks for the invitation to come and speak to you today so um UK hemp creete is my company and ISO hemp is um our partner in Belgium who make hemp creete blocks so I’m going to tell
You a little bit about their process later on um and we’re shortly going to be manufacturing those blocks in the UK and that’s why I’ve come to talk to you about them because you guys are hopefully our supply chain or those those of you who are farming
Um so uh that this is a house that um was built by us in uh 2018 um on Mainland orne where there is quite a lot of water around um so and I 100% agree with Mike’s um uh diagnosis of most of any problems you’ll find in a
Hemp Creed or hemp lime uh the terms are interchangeable at the moment really uh house will be to do with um moisture okay so um just a a little bit of background most of you know me I think already but this I’m in my I’m halfway through my second decade of building
With hemp and other biomaterials in the UK and we as a collective uh we the country uh England are approaching halfway through our third decade of building with this particular material so that’s a a thing to be celebrated so that’s an inside shot of the same house
As we were building it up so you can see the iso hemp blocks that have been built as a has an internal skin around and tied back to the not around sorry um lining and tied back to the structural timber frame of the building as hemp creete is not a loadbearing material you
Can think of it as a kind of mass Walling insulation material uh made by mixing building lime uh or or a formulated building line with um the raw stalk of the hemp plant which is chopped up as an aggregate in that material okay this particular house had an internal
Lining of um pre-cast ISO hemp blocks and then um an external skin of wet mixed hemp creete that was um it mixed and installed on site so you’re kind of combining the um best of both Wells okay so as I was discussing with Mike in the break when you’re wet mixing and casting
The material on site you then have a drying time on site and it’s sometimes the problems any problems that do arise will arise because Builders are kind of wanting to speed that process up mainly because the client wants to be in for Christmas um and so the uh this kind
This kind of combined buildup ensures you against that so you can you still have the benefits of this single cast homogeneous material around the outside of the building so you’d have no thermal bridging through different El of the building and uh it’s very easy to make airtight by applying a line render which
You saw in the first photograph but the inside is already dried so if necessary while the Hem Creed’s drying you can fit the windows and plaster and move in doesn’t slow um progress on site um it’s it’s not just us that are using hemp Creed blocks and in fact you might
Well recognize this photo and this was a a very certainly the ear example I’ve got a photograph of of a project involving hemp blocks and the company will be familiar I’m sure to lots of you in this part of the country I was actually born about four miles down the
Road from uh southw so it’s my kind of home brewery if you like so I think this is 2006 would you agree with that yeah so a little couple of years before I started um and this was built by a company called lime technology and again
That building is a mixture of hemp creek block and cast on site hemp Creed the the reason that um Brewery companies and other food companies the wine Society in stevenage also has a hemp creete Warehouse the reason um those companies are really interested in using it as a
Material is that the fabric of a hem Creek Building gives it some exceptional thermal and moisture performance characteristics which enable a kind of pass the fabric itself passively delivers a sort of regulated humidity and temperature inside the building which has obvious benefits if you’re storing um wine or beer or
Food um here’s a more recent example this is a um Cafe building that we built in well we didn’t build the building we built the hemp Walling system within it in uh the park in lincol here a few years ago 2017 I think um which again is
Built using a combination of hem creete blocks without the cast hem creete this time because we don’t consider cast on site to be suitable for kind of commercial scale um projects because of that drying time really so this in this case it combines um hem creete blocks
With a wood fiber board um external insulation shell which is then either rendered or brick clad um depending on the the elevation in theing um another slightly earlier project this one if anyone’s from Yorkshire you might know this one so this is um Williams Den up in the East
Riding which is a essentially a farm diversification project and it’s a big um kind of uh adventure play area it’s a great day out if with the kids or grandkids if you’re up that part of the world and the whole it’s it’s not just indoors it’s outside as well and it’s
All themed around natural materials um so again hemp creete blocks and wood fiber used on that project so um as I wanted to tell you a little bit more about the block system as Mike was saying I think you probably covered most of these off Mike but the the hemp hemp
Lime or hemp cre has some really exceptional characteristics um the main one being thermal performance so we’re going to talk about that in a in a little bit and I’m going to embarrass myself by showing a slide that probably originated from the University of bar a few years
Ago not really realizing that M was going to be in the room today um but yeah essentially so due to the fact that lime is used as the binder one of the really interesting things about hempcrete is that it doesn’t need any additional chemical treatment for rock resistance pest resistance or fire
Resistance okay so that’s a big one and clearly everyone in the construction industry has had their minds FOC fed on fire over the last few years sadly since Grenville Tower um as Mike was saying the the the hemp Crete envelope itself will passively regulate um internal
Humidity um which uh has lots of health and well-being benefits for building occupants um the thermal Comfort is really exceptional so I was down in uh South Deon on Wednesday visiting a building down there that was built last year and walked in and the internal in the temperature was like this building
Today and I said to them have you had the heating on at all yet and they said no um which is the expected answer because everything we’ve ever built just sits there at 18 between 17 and 19 degrees Centigrade all year round so it can be minus 10 outside it can be plus3
Outside and it just stays within that range um and that’s just from the fabric performance so when you start to think about um kind of passive solar Design Within the the design stage you can kind of increase that a little bit if you want to
Um so as Mike was saying one of the key things that we’ve all been working on over the last few years is reducing embodied carbon um within Construction Products clearly the thermal performance of the building reduces operational carbon so the the fuel that we’re using to heat buildings
Quite significantly and um as I’m sure most of you are aware globally um I think about 39% of global CO2 emissions are um uh associated with buildings okay so with and out of that 30% about 2third sorry 40% about 2third are the operational emissions associated with
Running the building um and the other um third is to do with the embodied carbon so the the carbon that gets emitted in the extraction of raw materials and manufacturing of products okay but in this case 80% of a of an ISO hemp block is RO hemp stalk okay um we also have
Some sort of manufacturing efficiencies that help us to reduce carbon so um the uh any kind of unused um or sort of material that isn’t fit for the market can be crushed and re and added back into the manufacturing process um the carbon footprint of H creete obviously varies from company to
Company uh every manufacturer will be um assessing it their own particular supply chain so um uh the for this particular product um there’s a a net 75 kilg of atmospheric CO2 that gets locked up in a cubic meter of hemp creete blocks and that is to do with uh largely to do with
The amount of CO2 that the hemp plant absorbs during its growth phase relative to other plants it’s growing very fast quite growing sort of 3 or 4 meters in 3 or 4 months and it’s holding itself up by very rapidly absorbing carbon and laying it down as uh cellulos in a
Really Woody stem okay so um we we’re going to find out exactly how much because I’m also haven’t got it on my slides today but I’m also a part of the um different varieties as they’re grown around the UK so um as Mike was saying a really important part of um taking a
Construction product product to Market is thorough testing and certification of that product not expecting you to kind of read all of the the the bits out of that today but have I got a I got a laser oh yeah yeah that works so just a really important important one essentially so
This is the this is the reaction to fire without any lime render or lime plaster on the product and that’s typically how you use it you create the wall from from the Hem creete blocks and then you would apply an internal line plaster and an external lime render or or any other
Finish you want directly onto the material so um with with a plaster applied it gets an A2 um reaction to fire which is the highest you can get if there’s any biom material at all in a product um and then in terms of fire resistance within buildings or you know
A fire break 120 mil block gives with plaster gives you 60 Minutes fire break and a 200 mil block gives you um uh two hour fire rating okay so um as uh you may have may not have picked up the bulk density the weight of the product is quite heavy for an insulation
Material so 340 kg per cubic meter in this case which is a sort of typical figure for hemp creting walls and um what that gives us is where’s it gone the specific heat capacity I’m missing that maybe it’s not on that on this basically it’s a it’s it the
Thermal performance is not just due to the U value the insulation value it also because of the line binder has a mass um and for that reason the phase shift this line here is uh this is in hours the phase shift is the time that it takes energy
To pass through the as heat to pass through the envelope okay so whereas if you had a very lightweight insulation material like for example P or any kind of lightweight insulation material um 200 mm of that material would have a phase shift of about three three and a
Half hours okay so that’s why if you kind of work in a modern well insulated building um you’ll be very comfortable till about lunchtime during the summer and then the building will start overheating because the heat is after that time has passed through the envelope and is now inside the room with
You and your insulation layer is now working against you and you’re cranking the airon up because it’s really uncomfortable okay so if we take the 20 centimeter or 200 mil block and we follow that down you’ll see that the phase shift is I can’t actually read it
From there I think 13 hours it’s usually 12 12 to 13 hours so the interesting effect that that gives us with due reference to Mr Lawrence um was demonstrated really neatly in um a paper from the University of b many years ago like 2010 or something like that um where they built
Two experimental buildings one filled with P insulation and one with hempcrete so this was 200 mm of hempcrete cast around the timber frame I’m not allowed to build walls that thin in the UK because it doesn’t meet current building RS for insulation value at all we’re building walls that are
Nearly twice that thickness but you can see that this unheated building or left unheated over a certain length of time you’ve got the external day night temperature in purple there fluctuating as you would expect uh on quite helpfully a 12-hour cycle okay with dial temperature change and then the internal um uh temperature
Inside that unheated building is staying much more static within a kind of 15 16 degrees um Centigrade range okay and that’s that’s the sort of visual um uh sort of underlining of that effect that I was talking about of that static internal temperature that we get in
Buildings so uh a little bit more detail about the products themselves as you probably saw from the tech sheet they come in a wide range of sizes that’s intentional to make the whole system a bit more flexible um we’ll come back to these interesting looking blocks with
Holes on in a second um so they’re range in size from 7 cenm which might be much more appropriate for a retrofit context right up to three um 300 60 mil and those can obviously be combined in a lot of different ways um I’ve included just because they they’re not it’s not
Included on the um tech sheet some sort of U value information okay and they’ve highlighted their the ones that um that they they consider to be passive okay and there’s a lot a lot of kind of focus on passive house as a concept in the UK because it’s been developed over many
Years is to have very low operational um energy okay but passive house is um a a certification system designed for lightweight insulation okay and if you’re using lightweight insulation that’s a logical place to get to you need to have stuff that’s super insulated and super airtight to maximize the potential performance of that
Building but the one issue with it is and this is partly due to the modeling software that they use but the um one of the issues with it is that because it’s a lightweight insulation it has a tendency to overheat in the summer okay and you will find that in passive house
Design there will usually be a big concrete floor slab or something to to put some Mass into the building to tr as as a heat dump during the hotter months and obviously people will use Purge ventilation to sort of release the heat with hemre that thermal mass is spread
Around equally around the envelope of the building okay um so a little bit about the manufacturing process so um ISO hm have been going for about nine years um they’ve recently about two years ago um built their second Factory so they they their first factory had um sort of um uh
Like a million blocks a year capacity and they’ve now stepped up to a five million blocks a year capacity um so let’s break that down so three raw materials water pemp and a line formulated line binder um the uh as I said before any blocks which don’t meet the kind of alterated
QA standard will get CR crushed they also and whoever was talking about um uh companies capitalizing on these things so as well as crushing the material and putting it back into the next manufacturing cycle they’ve also realized that crushed but preed hemp Crete is quite a good loose fill
Insulation material so they have a separate product which gets sold um in that form the lime is a mixture of um air lime and hydraulic lime okay roughly roughly 550 within within the the mix of the binder um and there’s a a huge Silo uh two huge silos on site for
Storing that material which gets automatically fed through to the mixing um facility inside obviously so the the the the three three materials the lime the hemp and the water come together and get mixed and then that material is dumped into an automated production line which spreads it into molds and it sort
Of robot arm comes over and presses it and then uh any sort of non there’s a a stage where they get measured any non-compliant blocks get pushed off by the robot and then um those blocks move along and and are sort of stacked neatly on a pallet by another robot and then
The pallet itself um gets lifted by a machine into um a curing room um and after 24 hours of initial hardening which is a function of the hydraulic line they will then um get stacked onto pallets um and the full pallet is then set outside is covered stabilized and covered and set outside
To go through the drying process and the air lime in the mix then reabsorbs some of the carbon that was given off when that line was burnt okay and then finally after couple of months drawing time they get delivered to site and they’re used in a range of context so
Here’s another Dom itic building with a timber frame and hemp blocks being um built up around it there’s the finished article um steel frame and hemp creete blocks this is where the the different sizes of block come in very useful use come in very handy because you can kind
Of design any sort of sort of bits where you’re building around the the steel frame structure can easily be done with that that’s the same building again they’re also suitable for a CLT structure which kind of had a a real popularity a few years ago I think people are now
Realizing it’s not quite as sustainable as they hoped it would be um but you there you have a CLT structure and hemp creete blocks being built up the side and there’s the finished building we also I’ll run through this a bit quickly because I’m not sure about
Time but um this these funny shaped blocks were to do with this system so on the continent it’s less usual here but on the continent even in domestic buildings it might be more usual to cast a a rebar concrete frame as the structure in a building and in terms of scaling H
Creete in um scale house building that’s that’s quite uh has quite obviously impact your carbon footprint but it has the ability to make the build a lot cheaper so you have blocks that are deliberately formed that you can build with the hempcrete blocks which are self-supporting and as you go up you um
Cast to reard concrete frame inside so a couple of examples of that on site so you can get an idea immediately how that works and then this is our first hemp house in this country which was um designed by an architect called Cathy Curran in London a few years
Ago it can also be as I was saying earlier be used in retrofit either as external wall insulation because they’re very as a p as a material is very resist to um water as M was saying as long as you don’t trap water in it it can also
Be used in internal um wall insulation context and this is a couple of shots of a an apartment blocking um Brussels so commercial retrofit context basically so thank you and uh don’t know if I’ve got time for questions but I’m here all day so you know where I am thank you Alex